05-09-2011, 07:33 PM
Join Date: Sep 2005
Total Cats: 1,528
Well, first things first. If you re-used the Miata's stock coil wiring, there's already a cap on the supply line to the coils. For the time being, forget about adding anything extra until we get the board to stop emitting fire and components. Also, 47uf is nothing. Those of us running COPs are using huge values- I can't recall the exact values I used, but I think it was 2x 4,700 uf in parallel (9,400 uf equivalent) at probably 35v. (I think I just bought two of the largest caps RadioShack had.)
Now, onto snap, crackle and pop...
R37 is the 0.05 ohm resistor that's used as a current-sense shunt in injector circuit 2. Its purpose in life is to help prevent things from blowing up when you have a short-circuit across an injector, by signalling Q15 to remove the gate drive current from Q5 when it detects more than 14 amps coming down that line.
Q12 is part of the flyback-damping circuit for INJ2. Again, it's there to prevent harm, not to cause it.
And D10, well, that guy is in series with the 12v coming into the board just before the regulator. It is after hole S12, but before hole S12C.
I'm wondering if you have multiple problems...
For starters, do you have any wires connected to point S12C on the main board?
Are R20, Q5, Q15, Q11, D7 and D20 all installed correctly and without any solder blobs? If I turn my head and squint just right, I can see a potential path for some damage there, although worst-case should be a short from just before D10, not after it...
How about D12, C16 and U5- are all those guys straight and clean? A short across any of the three would nuke D10. So would a short across both D9 and either C17 or C18, but that seems improbable.
Pictures, man! Nice, clear, high-resolution pictures.